During a communication link set up between two communication devices, for example during a telephone call, audio signals are usually exchanged between a transmitter communication device (usually called “source” in communication engineering) and a receiver communication device (usually called “sink” in communication engineering) in real time. During this process, the transmitter communication device usually has no possibility of influencing the handling (for example the processing of the received audio signals, for example for outputting the audio signals) of the received real-time data selectively in any way at the receiver communication device.
Conventionally it is necessary that, when the type of control information is changed which is coded together with the useful signal and transmitted, both the entire coder and the entire decoder are changed.
This is complicated and very expensive. If the coder and decoder are constructed as hardware components, both hardware components would have to be exchanged in the source and in the sink.